This invention relates to the field of partially-overlapping heat-sealable roll roofing material and the like and, particularly, to an improved machine for handling and sealing such material during installation.
In the area of welding and sealing various heat-sealable materials such as thermoplastics, the prior art is full of various methods and apparata designed and constructed with specific objectives in mind. In this regard a patent issued to Sourber, U.S. Pat. No. 3,047,050, discloses a hand-held hot air welding apparatus designed for various strip-welding operations and including a roller adapted to sealably press the strip in position after it is heated. Alfter et al. U.S. Pat. No. 3,962,016, discloses a process and hand-held apparatus for joining abutting thermoplastic synthetic-resin foam structures for sheets by sealably pressing a heated metal strip onto the junction zone between two foam sheets. In this same regard, Werstlein, U.S. Pat. No. 3,853,669, and Wenzel U.S. Pat. No. 3,580,789, also disclose specialized welding gear for use with various hand-held thermoplastic welding apparata.
The prior art also reveals various other more complex apparata also adapted for very specific heat sealing purposes. One such apparatus is found in Bergstein et al., U.S. Pat. No. 2,676,642, which discloses a complicated unit and method for heat-sealing films including the operation of continuously heating an endless belt. Hakomaki et al., U.S. Pat. No. 2,635,673, also discloses a complex controlling device and tensioning means for seaming layers of various thermoplastic materials. In this same regard, Jacobi, U.S. Pat. No. 3,654,043, and two patents issued to Kauer, U.S. Pat. Nos. 3,097,986 and 3,060,077, disclose processes and various complex apparata for heat sealing entire sheets of such thermoplastic material in which a roll of the material is carried on the apparatus itself and is sealably joined to either another surface or another sheet of the material by means of heat-sealing wheels or an elongated burner tube.
In the area of industrial roofing and flooring applications and the like, partially-overlapping heat-sealable roll or sheet material is often used in which the edge portions of adjacent laid sheets of the roll material form an overlapping joint which can then be heat sealed or fused to form a protective sealed surface for the given roof or floor. An example of such a product is a Koppers Multipurpose Membrane, commonly referred to as KMM, manufactured and marketed by the Kopppers Company, Inc. of Pittsburgh, Pa. 15219. The Standard KMM membrane is a five-layer laminate composed of a thick, flexible plastic core protected on each surface by a layer of modified bitumen material and an outer film of polyethylene. An Aluminum KMM product is also marketed by Koppers Company, Inc. also involving a five-layer laminate similar to the above product except that the top surface is a heavy, embossed aluminum foil while the bottom surface remains a film of polyethylene. A strip of aluminum foil about 4 inches wide, however, is removed along one side of the membrane in order that the overlapping contact surfaces will both be the bitumen material with only the thin polyethylene covering.
In the application of either KMM product, sheets are first rolled out onto the roof, foundation, plaza or other substantially level construction surface with the edge portions of each adjacent sheet of material being overlapped to form a joint. Each joint can then be heat sealed to form an excellent waterproofing membrane that protects the surface from the various weather conditions. In some applications, particularly with the aluminum KMM product, it is also desirable and advisable to use a cold adhesive to cement the individual sheets to the covered surface in addition to heat sealing the overlapping joints.
The present state of the art in handling and sealing such partially-overlapping heat-sealable products as both the Standard and Aluminum KMM membranes is for workmen to sufficiently heat the contact surfaces on the overlapping edge portions of the material by using some variety of hand-held hot air or gas welding gun and then to manually press the surfaces together thereby completing the sealed joint. This method of application is highly inefficient and time consuming and results in both increased labor costs and higher prices to the consumer.
One machine presently available, of which applicant is aware, that attempts to solve this problem is an automatic hot air welding machine marketed under the trademark "LEISTER-VARIUS" and available in the United States through the Bryan R. White Co., Inc. of 15075 Weststate, Westminster, Calif. 92683. A copy of a published advertising brochure available through the Bryan R. White Co., Inc. regarding the "LEISTER-VARIUS" machine is submitted herewith and is expressly incorporated herein by reference as applicant's best knowledge of the present state of the art with regard to this machine. The "LEISTER-VARIUS" machine itself, with the overlap welding accessory set attached thereto, apparently moves along one side of the overlapping edge portions of the roofing material and merely blows hot air in the direction of the overlapping joint and then presses the edge portions together with its relatively small side-mounted trailing wheel to thereby form the sealed joint.